中山市地下水饮用水源地及其周边水化学特征及形成机制

Hydrochemical characteristics and formation mechanism of potable groundwater sources in Zhongshan City and its surroundings

为了探究地下水饮用水源地水质现状,运用数理统计、piper图、Gibbs图、环境背景值统计等方法研究中山市地下水饮用水源地及其周边水化学特征及形成机制。结果表明,研究区内地下水呈现弱酸性和低矿化度,Na^(+)和HCO_(3)^(-)是地下水中主要离子,水化学类型以HCO_(3)-Na·Ca型为主。水化学组成受大气降雨-岩石风化联合作用,阳离子交换作用较为强烈。长期大量的酸雨、包气带土壤及含水层对酸沉降的缓冲能力较差和碱土金属、CO_(2)以及碳酸盐的水解是造成地下水pH值降低的主要原因。

To investigate the current water quality of potable groundwater sources,this paper utilizes methods such as mathematical statistics,Piper diagrams,Gibbs diagrams,and environmental background value statistics to study the hydrochemical characteristics and formation mechanism of groundwater drinking sources in Zhongshan City and its surroundings.The results show that the groundwater in the study area is weakly acidic and low in mineralization,with Na^(+) and HCO_(3)^(-) being the main ions.The hydrochemical type is predominantly HCO_(3)-Na·Ca.The chemical composition of the water is influenced by the combined effects of atmospheric precipitation and rock weathering,with a strong cation exchange reaction.The main reasons for the decrease in groundwater pH value are the long-term abundance of acid rain,the poor buffering capacity of the soil and aquifer in the vadose zone against acid deposition,and the hydrolysis of alkaline earth metals,CO_(2) and carbonates.